Draco SBR project

I have a draco that I'm thinking about SBR'ing. Before i send out for my stamp. i just wanna ask a few questions. My draco isnt pretapped for an underfolder like i hear some are. so which would be cheaper. to just go for the underfolder. or put a sidefolder on it? i'd prefer the sidefolder but i just wanna check price/labor first?
tips?

I like sidefolders better, but side folders and underfolders suck to shoot, you just cant get a good cheek weld and they will wear out the side of your face.

Most side folders are too short for me so I went with the side folding collapsible Magpul that works perfectly and it dosent look too bad.
http://i18.photobucket.com/albums/b130/HotGuns/003.jpg?t=1303685300